Poster B100, Sunday, March 26, 8:00 – 10:00 am, Pacific Concourse
The Lateral Parietal Cortex Processes both the Encoding and Retrieval of Spatial Long-Term Memories
Oliver Gray1, Daniella Ryding1, Daniela Montaldi1; 1University of Manchester
Our perception of the visual environment involves attending to information presented simultaneously in a variety of locations. Healthy individuals often show a subtle but significant bias to preferentially allocate attention to the left side of both visual and remembered space. These effects are known as perceptual and representational pseudoneglect, respectively. Surprisingly, the possibility that common mechanisms explain both biased perceptual attention allocation (perceptual pseudoneglect) and biased long-term memory retrieval (representational pseudoneglect) has never been explored. The lateral posterior parietal cortex has consistently shown activation during successful retrieval of episodic memories, using functional magnetic resonance imaging (fMRI). The investigation into this activation has yet to employ a method challenging attention allocation (and inducing a pseudoneglect bias) at encoding, and also requiring retrieval of episodic, long-term memory. We utilised fMRI whilst manipulating the location of images of objects at encoding (left versus right visual field) and employing a delayed forced-choice recognition task. We compared activity in areas of the brain associated with the allocation of attention with those associated with long-term memory retrieval. Critically, accuracy of delayed object recognition was greatest for items presented in the left visual field at encoding. Furthermore, we observed hemispheric lateralisation of cortical reactivation in the lateral parietal cortex during the retrieval of correctly identified, previously encountered images that reflected the side of visual space where the object was originally presented. This data provides a novel perspective on the lateral parietal cortex and provides an important complement to current theories of the neural bases of recognition memory.
Topic Area: LONG-TERM MEMORY: Episodic